Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M3/00—Conversion of dc power input into dc power output
  • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
  • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
  • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
  • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
  • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
  • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
  • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
  • H02M3/33592—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M3/00—Conversion of dc power input into dc power output
  • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
  • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
  • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M3/00—Conversion of dc power input into dc power output
  • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
  • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
  • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
  • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
  • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
  • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Definitions

• the present invention relates to a circuit arrangement for generating drive signals for a synchronous rectification switch of a flyback converter.
• the present invention further relates to a method for generating at least one drive signal for at least one synchronous rectification switch of at least one flyback converter, in particular at least one actively clamped bidirectional flyback converter.
• This actively clamped bidirectional flyback converter is based on the reference document "Actively-Clamped Bidirectional Flyback Converter” by Gang Chen, Yim-Shu Lee, S. Y. Ron Hui, Dehong Xu, Yousheng Wang, IEEE Transactions on Industrial Electronics, volume 47, number 4, August 2000, pages 770 to 779.
• This converter does not include any current sensors.
• the on-time of the synchronous rectifier switch is taken from the pulse-width- modulator in combination with a "turn-on delay" sub-circuit.
• EP 1 148 624 Al describes an integrated circuit to drive a power M[etal- ]O[xide-]S[emiconductor]F[ield]E[ffect]T[ransistor] acting as synchronous rectifier (cf. also Fabrizio Librizzi, and Pietro Scalia, "STSRx family: Mixed-signal ICs to drive synchronous rectifiers in isolated SMPSs", STMicroelectronics, application note AN1288, July 2000).
• US 6 462 965 Bl discloses a sub-circuit to drive a power MOSFET as synchronous rectifier switch by means of one current transformer per output.
• US 2003/0090914 Al reveals a circuit including a special sub-circuit to drive a power MOSFET as synchronous rectifier by means of a second current shunt sensor.
• Texas Instruments' integrated control circuit type UCC2891 and UCC2897 includes only two time delay functions to control the on-time of the two power semiconductors on the primary converter side (cf. Texas Instruments, UCC2891 Current Mode Active Clamp PWM Controller, data sheet, July 2004; Texas Instruments, UCC2897, Current Mode Active Clamp PWM Controller, data sheet, April 2005).
• the use of synchronous rectifier switches is only illustrated for the application of a forward converter and does not include control circuits for the timing of the synchronous rectifier switches.
• US 6 888 728 B2 includes timing circuits on the secondary side of the transformer.
• the timing circuits include a comparator requiring an additional supply voltage on the secondary side of the power converter. This overall effort of sub-circuits to drive the synchronous rectifier switches on the secondary side of the transformer is very high and generates significant costs.
• the greatest disadvantage of US 6 888 728 B2 is the higher component effort meaning also higher cost.
• JP 2005-198438 A describes a load resonant half-bridge converter with synchronous rectification.
• the component count of this known circuit is very high; apart from that, the load resonant converter includes a second power transformer plus a shunt resistor both generating additional power losses and thus increasing the thermal management effort.
• the greatest disadvantage of JP 2005-198438 A is the use of a second power transformer to monitor the input current of the load resonant circuit on the secondary side of transformer; this generates significant loss in the second power transformer.
• Particular embodiments may result in an improved and simpler thermal management combined with a significant cost reduction as well as with a higher efficiency.
• Advantageous embodiments of the present invention are principally based on the idea to control a synchronous rectifier, more particularly to provide a control circuit for at least one actively clamped bidirectional flyback converter with a synchronous rectifier and with a transformer isolation making use of an oscillating signal which controls the synchronous rectification switch.
• At least part of the flyback converter can be turned-off with a variable delay time.
• the delay time interval is a function of the relative converter power level with minimum delay, which is independent of the power level.
• At least one voltage sensor can measure the drop across the low side switch on the primary side which gives a digital "high" output in case the sensed drain- source voltage of said low side switch is negative due to the fact that the current in said low side switch is flowing from source to drain.
• this digital output of the voltage sensor is ORed with at least one second signal to drive the synchronous rectifier switch.
• Said second signal is a delayed signal of at least one inverse P[ulse-]W[idth]M[odulation] signal.
• a further advantage of certain embodiments of the present invention is that the cost of the circuit to drive the synchronous rectifier MOSFET can be significantly reduced; in addition thereto, also the power losses of the actively clamped bidirectional flyback converter with synchronous rectification can be reduced.
• the latter advantage can be used to reduce the effort for thermal management, i.e. to transfer the heat out of the preferably closed housing of the circuit arrangement of the present invention.
• advantageous embodiments of the present invention enable an improved design freedom for flat displays, such as for L[iquid]C[rystal]D[isplay] T[ele]V[ision]s, enable compact L[ight-]E[mitting]D[iode] lamp drivers with low cooling effort, and improve the functionality of power conversion modules.
• Embodiments of the present invention can be applied in order to improve electronic circuits in consumer products, such as in L[iquid]C[rystal]D[isplay] T[ele]V[ision]s or in L[iquid]C[rystal]D[isplay] computer monitors, in L[ight-]E[mitting]D[iode] lamp drivers, in battery chargers and in battery dischargers.
• Fig. 1 schematically shows a principle diagram of a preferred embodiment of a circuit arrangement according to the present invention being operated according to the method of the present invention
• Fig. 2 schematically shows a principle diagram of qualitative time functions in steady state, referring to the method of the present invention.
• FIG. 1 shows a block diagram of a preferred embodiment of the circuit arrangement 100 according to the present invention.
• the circuit arrangement 100 comprises an actively clamped bidirectional flyback converter with four power semiconductors Ql, Q2, Q3, Q4; each of these power semiconductors Ql, Q2, Q3, Q4 is implemented as a transistor unit, in particular as a metal-oxide semiconductor (MOS) or as a metal-oxide semiconductor field effect transistor (MOSFET).
• MOS metal-oxide semiconductor
• MOSFET metal-oxide semiconductor field effect transistor
• the second transistor Q2 acts as synchronous rectifier;
• the fourth transistor Q4 is a semiconductor switch or active clamping switch designed to actively confine or to actively delimit the voltage load of the synchronous rectification switch Q2.
• a single control circuit generates the driver signals to turn-on and to turn-off all four transistors Ql, Q2, Q3, Q4 of the flyback converter.
• the flyback power converter is addressed because such addressing is the most cost-effective circuit topology being a key feature for the dominant range of applications.
• the so-called power transformer TrI in the flyback converter is practically a coupled inductor; that, and some other functions, is the reason why the flyback converter does not have the disadvantages of switched mode power supplies derived from the forward-based converter topology; the disadvantages of forward-based topologies is the key objective of US 6 888 728 B2 to effectively prevent the generation of through currents in the two series connected synchronous rectifier switches.
• the circuit arrangement 100 according to the present invention has a significant lower effort to generate drive signals for the synchronous rectifier switches being realized by the second transistor Q2 as well as by the fourth transistor Q4. These are practically the gate drive transformer Tr2 (with at least one preconnected driver IC4) and the optocoupler IC5 on the secondary side of the transformer TrI .
• a voltage sensor VS is implemented as a comparator for measuring the voltage drop of the first transistor Ql.
• the voltage sensor VS generates a logic output signal Vn being "1" if the voltage sensor VS measures a negative drain- source voltage of the first transistor Ql, and being "0” if the voltage sensor VS measures a vanishing or positive drain- source voltage of the first transistor Q 1.
• the voltage sensor VS can detect a negative drain-source current at the first transistor Ql.
• a negative current Ii(t) (cf. Fig. 2) is present at least in the time interval from t3 to t5 (cf. Fig. 2) because of the active clamping principle.
• Fig. 1 depicts a first integrated circuit ICl, namely a high voltage driver for power metal-oxide semiconductor field effect transistor (MOSFET) or insulated gate bipolar transistor (IGBT) driver with independent high and low side referenced output channels; the proprietary high voltage insulator coating (HVIC) technology as well as the latch immune complementary metal oxide semiconductor (CMOS) technology enable a ruggedized monolithic construction of said first integrated circuit ICl.
• Q2 are the two input signals of a logic unit L5, said logic unit L5 comprising an OR function.
• Q2 (cf. Fig. 2) being the drive signal to turn-on and to turn-off the second transistor Q2.
• This digital output Vn of the voltage sensor VS is ORed with a second signal to drive the synchronous rectifier switch Q2 wherein this second signal is a delayed signal of the inverse P[ulse-]W[idth]M[odulation] signal; the inverse P[ulse-]W[idth]M[odulation] signal is generated by an inverse P[ulse-]W[idth]M[odulation] unit PWMi being a component of a second integrated circuit IC2, namely of a monolithic timing circuit.
• a shunt resistor is not required to generate the timing signals of the synchronous rectifier switches Q2, Q4. Instead, the negative drain-source voltage of the first transistor Ql is additionally monitored with the voltage sensor to finally determine the on-time of rectifier switch Q2.
• a sixth integrated circuit IC6 namely a three-terminal programmable shunt regulator diode is arranged at the output stage of the circuit arrangement 100.
• This monolithic IC6 voltage reference operates as a low temperature coefficient zener diode being programmable from reference voltage to 36 Volt with at least one external resistor, preferably with two external resistors.
• a seventh integrated circuit IC7 comprising an optocoupler is arranged behind an eighth integrated circuit IC8.
• the second transistor Q2 works as synchronous rectification switch which is turned-off at time point t3 with the falling edge of the output signal of the inverse P[ulse-]W[idth]M[odulation] unit PWMi.
• the third transistor Q3 is also turned-off, and the changing voltage V DS .
• QI (cf. Fig. 2) changes the slope of the current in the second transistor Q2, with said changing voltage V DS .
• QI becoming slightly negative between in the time interval from t4 to t5 (cf. Fig. 2) because of the active clamping principle.
• the second transistor Q2 is turned-off with a variable delay time.
• the delay time interval is a function of the relative converter power level.
• a minimum delay time is adjusted with the second resistor R2 in a time delay circuit TDC in Fig. 1.
• This time delay is independent from the power level.
• Fig. 1 depicts the monolithic timing circuit IC2 providing full compatibility with complementary metal oxide semiconductor (CMOS), transistor-transistor logic (TTL), and metal oxide semiconductor (MOS) logic and - operating at frequencies up to two Megahertz.
• CMOS complementary metal oxide semiconductor
• TTL transistor-transistor logic
• MOS metal oxide semiconductor
• the respective third integrated circuit IC3 providing positive quadruple 2-input AND function is arranged between the first integrated circuit ICl and the time delay circuit TDC as well as behind the time delay circuit TDC.
• the above-identified control technique does not prevent a conduction of the inverse diode of the second transistor Q2 for example from time point t5 to time point t6 in Fig. 2.
• a special control technique generates the drive signal of the synchronous rectifier power semiconductor to be used in the actively clamped bidirectional flyback converter according to the present invention.
• This control technique requires a minimum effort to sense electrical signals.
• the first power semiconductor (Ql) may in particular be at least one first transistor unit, for example at least one first metal-oxide semiconductor (MOS) or at least one first metal-oxide semiconductor field effect transistor (MOSFET).
• the second power semiconductor (Q2) may in particular be at least one second transistor unit, for example at least one second metal-oxide semiconductor (MOS) or at least one second metal-oxide semiconductor field effect transistor (MOSFET).
• the third power semiconductor (Q3) may in particular be at least one third transistor unit, for example at least one third metal-oxide semiconductor (MOS) or at least one third metal-oxide semiconductor field effect transistor (MOSFET).
• the fourth power semiconductor (Q4) may in particular be at least one fourth transistor unit, for example at least one fourth metal-oxide semiconductor (MOS) or at least one fourth metal-oxide semiconductor field effect transistor (MOSFET).
• the transformer unit (TrI) may in particular be at least one power transformer.
• the drive signal for the synchronous rectification switch may be generated as a function of at least one oscillating signal controlling the synchronous rectification switch, of at least one constant delay time, of at least one variable delay time, in particular of the detection of the current Il(t) in the primary winding of the transformer unit (TrI) generating the variable delay time, and of at least one Boolean OR function, in particular provided by at least one logic unit (L5).
• the first integrated circuit (ICl) may in particular be at least one high voltage driver of power metal-oxide semiconductor field effect transistor (MOSFET) or insulated gate bipolar transistor (IGBT) driver.
• the second integrated circuit (IC2) may in particular be at least one timing circuit, for example at least one monolithic timing circuit.
• the fourth integrated circuit (IC4) may in particular be at least one diode or driver, for example by at least one rectification diode.
• the fifth integrated circuit (IC5) may in particular be at least one optocoupler unit.
• the sixth integrated circuit (IC6) may in particular be at least one programmable shunt regulator diode, for example at least one three-terminal programmable shunt regulator diode.
• the seventh integrated circuit (IC7) may in particular be at least one optocoupler.
• ICl first integrated circuit
• MOSFET metal-oxide semiconductor field effect transistor
• IGBT insulated gate bipolar transistor
• timing circuit for example monolithic timing circuit IC3 third integrated circuit, in particular providing positive quadruple 2-input AND function
• IC4 fourth integrated circuit in particular diode or driver, for example rectification diode
• IC5 fifth integrated circuit in particular optocoupler IC6 sixth integrated circuit, in particular programmable shunt regulator diode, for example three-terminal programmable shunt regulator diode
• IC7 seventh integrated circuit in particular optocoupler or optocoupling unit
• Ll first logic unit, in particular comprising AND function
• L2 second logic unit in particular comprising AND function
• L3 third logic unit in particular comprising AND function
• L4 fourth logic unit in particular comprising AND function L5 fifth logic unit, in particular comprising OR function
• Ql first power semiconductor in particular first transistor unit, for example first metal-oxide semiconductor (MOS) or first metal-oxide semiconductor field effect transistor
• Q2 second power semiconductor in particular second transistor unit, for example second metal-oxide semiconductor (MOS) or second metal-oxide semiconductor field effect transistor (MOSFET), of flyback converter Q3 third power semiconductor, in particular third transistor unit, for example third metal-oxide semiconductor (MOS) or third metal-oxide semiconductor field effect transistor
• MOS metal-oxide semiconductor
• MOSFET metal-oxide semiconductor field effect transistor
• Q4 fourth power semiconductor, in particular fourth transistor unit for example fourth metal-oxide semiconductor (MOS) or fourth metal-oxide semiconductor field effect transistor (MOSFET), of flyback converter
• MOS metal-oxide semiconductor
• MOSFET metal-oxide semiconductor field effect transistor
• TDC time delay circuit TrI first transformer unit in particular power transformer
• Tr2 second transformer unit in particular gate drive transformer

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Dc-Dc Converters (AREA)
• Rectifiers (AREA)
• Control Of Eletrric Generators (AREA)

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• 2007
  • 2007-05-25 DE DE602007011925T patent/DE602007011925D1/de active Active
  • 2007-05-25 JP JP2009512738A patent/JP5285602B2/ja not_active Expired - Fee Related
  • 2007-05-25 EP EP07736016A patent/EP2030310B1/fr not_active Ceased
  • 2007-05-25 WO PCT/IB2007/051980 patent/WO2007138537A2/fr active Application Filing
  • 2007-05-25 KR KR1020087031852A patent/KR20090014307A/ko not_active Application Discontinuation
  • 2007-05-25 CN CN2007800201795A patent/CN101461122B/zh not_active Expired - Fee Related
  • 2007-05-25 AT AT07736016T patent/ATE495571T1/de not_active IP Right Cessation
  • 2007-05-25 US US12/302,032 patent/US8279637B2/en not_active Expired - Fee Related
  • 2007-05-28 TW TW096119069A patent/TWI443954B/zh not_active IP Right Cessation

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